The most sales of velombiles seem to be to folks who want to ride fast. This is not suprising as early adopters would mostly be serious cyclists and one of the primary reasons for considering a velomobile would be to go faster. What I am thinking of is something along the lines of a Milan/WAW/Evo K. It would have to have very good speed potential and still carry just enough gear to go touring.
As for overall size it would similiar to the WAW. With a shorter nose and a longer pointer tail. I would also have a bit more room for my feet, knees and shoulders. I am 6'2" and have size ten and half feet so I don't quite fit the WAW. I could modify the WAW by putting in bumps for my knees and shoulders but it just seems wrong to do this to such a nice machine. Better that it eventually goes to some one who fits it properly. It should be possible to have a smaller frontal area than the Quest and still have enough room for gear. From the bit I have ridden the WAW there is quite a bit to be said for its great cornering ability. This comes about by its wider stance and front wheels that are canted in quite a bit. Having you sit right on the floor helps too.
It is very tempting to go with open wheel wells to decrease the turning raduis and make servicing the front wheels, brakes and suspension simplier. Open wheel wells can be quite efficient provided that the wheels are nicely faired into the body with very little space around the tires. The Evo K seems to verify that open wheel wells can be quite quick. The best way to get this result may be to build the shell without the wheel wells and then glue them in afterwards. Once the wheels are installed cut the opening to just fit around the tire. You could even adjust the size of the opening with an add on flat panel if you used bigger tires in winter and then switched to faster ones for summer time riding. The big advantage is in how I would fabricate the bottom half as it is quite a simple part to vaccum bag or infuse without having to work around the wheel wells. Making the wheel well as a separate unit would also simplify making this part. The risk of not having successful parts would be reduced. When you are vaccuum bagging or infusing you either get very good parts or junk you have to throw away. What happens if you loose vaccuum at a critical point is the part expands about 30% and fills with air.
My preference is for a head out velo but design it so a racing hood could be added for speed freaks. I prefer the slightly bigger head opening so you can see inside the velo when riding with the roof on. The size I have on the Borealis seems about right. This with a small foam cover for use in the most inclement conditions might be the best all round compromise. The head opening should be just large enough so you can crawl out of it if necessary. The size of the door section should be large enough to make getting in and out easy. Rather than go with a hinged door one that just lifts on and off is worth trying. If it could just snap in place that may be ideal. It should also sit on a substantial foam gasket so it doesn't rattle. If it was just long enough so it could be made in different sizes depending on the height needed to clear your knees you would have the option of customising the size of the velomobile a bit. If you did the same with the section where your feet are with a removeable cover you would would gain easy access to the front derailleur, headlight and a bit more usefull storage space in front of the wheel wells.
Suspension on all three wheels. While I would like to develop my concept for a carbon/basalt fiber spring front suspension it will most likey have the standard front suspension as found in other velos. The time and effort to develop this is hard to justify when velomobiel.nl makes a very good unit. Rear suspension should be an air shock so the rider can personalize it to suit them. The rear swing arm is best if not single sided so you have the option of using a Rohloff or rear hub motor. Structurally the double sided swing arm should be easier to implement. If the rear swing arm can be pulled out of the bottom of the shell so changing the rear tire would be the same as on a normal trike. One would have a removeable cover over this opening to clean up the air flow and keep everything clean.
Ground clearance of around 10 to 12 cm. Some cars are in this range for ground clearnace. This will make it a very practical vehicle as it will handle most roads with ease. Just the occassional speed bump that causes cars problems too may be an issue.
Reverse gear would still be with at least one foot hole open. The mould would have bumps for both feet so you then have the option of adding reverse or not.
Seat could be made easily removeable to make gear storage and cleaning the velombile easier. If you can take the seat with you it would make the velmobile unrideable.
This would be a monocoque structure with all the bike parts fitted to it. There would be no separate frame except for the rear swing arm and a carbon front boom assembly. Constuction would be out of kevlar and carbon fiber with some honeycomb or foam cores where necessary. To get the most performance out of these materials the parts would be vacuum bagged or infused. We have been looking into an epoxy resin system that seems safer to use than previous offerings. It has very high elongation which would help to build a very tough shell. There is a epoxy clear cost option that could add a very minimum of weight or even a paint that can be sprayed in the mould that would be lots lighter than gel coat. In a few months there is an epoxy gelcoat coming from this manufacturer that can be bent into a one inch radius without cracking. With any of these options spider cracks common in gel coat would no longer occur. Target weight of less than 25 kg. Cost is unknown at this point but it would be very competitve. Chances of this happening soon are quite low.